Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet
Product codes
AT91SAM9N12-EK
519
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
33.5
Typical Connection
Figure 33-2. Board Schematic to Interface Device Peripheral
33.5.1 USB Device Transceiver
The USB device transceiver is embedded in the product. A few discrete components are required as follows:
the application detects all device states as defined in chapter 9 of the USB specification;
VBUS monitoring
to reduce power consumption the host is disconnected
for line termination.
33.5.2 VBUS
Monitoring
VBUS monitoring is required to detect host connection. VBUS monitoring is done using a standard PIO with internal pull-
up disabled. When the host is switched off, it should be considered as a disconnect, the pull-up must be disabled in order
to prevent powering the host through the pull-up resistor.
up disabled. When the host is switched off, it should be considered as a disconnect, the pull-up must be disabled in order
to prevent powering the host through the pull-up resistor.
When the host is disconnected and the transceiver is enabled, then DDP and DDM are floating. This may lead to over
consumption. A solution is to enable the integrated pull-down by disabling the transceiver (TXVDIS = 1) and then remove
the pull-up (PUON = 0).
consumption. A solution is to enable the integrated pull-down by disabling the transceiver (TXVDIS = 1) and then remove
the pull-up (PUON = 0).
A termination serial resistor must be connected to DDP and DDM. The resistor value is defined in the electrical
specification of the product (R
specification of the product (R
EXT
).
R
EXT
R
EXT
DDM
DDP
PIO
27 K
47 K
Type B
Connector
1
2
3
4
5V Bus Monitoring